Have been having this trouble since I installed 2014 and happened again this morning. Thought previously Inventor was having trouble with my 2012 files but the IDW I tried to open this morning I have edited before.
I opening the main assy, opened a sub assy, made a few changes then tried to open the IDW file. The windows hourglass displays for as long as I am willing to wait. I click again and the screen goes gray over my assy and Inventor comes to a complete halt.
I have to use Windows Task Manager to shut Inventor down and open the IDW file first. SAfter I get an IDW open it seems I can open more of them until it happens again for no reason and no logical sequence.
Update 2 did not fix the problem. The same IDW file I edited this morning still took Inventor to a complete standstill.
Also when I check in my main assy to our vault Inventor crashes checking in the top assy IAM file. Everything else seems to be updated in the vault. Interestingly I got that IDW file open and when checking it in the main assy IAM file is checked in.